The CommBank Matildas have been beaten by Mexico 1-0 in their first of two matches against the North American opponent.
Substitute Diana Ordonez's injury-time goal proved the difference in the end-to-end affair on a cold winter night in Newcastle.
Joe Montemurro named a similar starting side to the one that played in Australia's last match at home against Japan in the AFC Women's Asian Cup Final.
Just two changes were made with Emily van Egmond introduced in the midfield and Amy Sayer adding an extra element in attack.
Ellie Carpenter was given the armband in her home state as the fullback notched up her 100th international appearance for the CommBank Matildas.
The early threats came through Caitlin Foord and Sam Kerr, with the duo combining through the crossing of the former toward the latter.
However, Mexico could break quickly, and after 15 minutes, the away outfit forced goalkeeper Mackenzie Arnold into a reaction save at her far corner.
The Mexican waves continued five minutes later, with Steph Catley's last-man heroics required to deny the goal-ward run of Kiana Hernandez.
Australia would respond this time through the runs of Ellie Carpenter down the right flank. Her sprints and crosses could not find a connection as both sides remained goalless at the break.
Within ten minutes of the restart, Sam Kerr was presented with two quality opportunities in the air, with the striker producing two headers on target, both of which were saved smartly.
Joe Montemurro looked for experience from the bench to break open the game, introducing Hayley Raso on the hour mark.
The winger's impact was immediately evident, playing a quality ball to Kerr, who flicked on target, requiring a save by the keeper.
Eventually she would get on the end of a passing move, darting down the right touchline, finding Sam Kerr's pass before firing her shot into the side netting.
Charlize Rule was next to be introduced as the CommBank Matildas looked to flood the field with attacking options. She was soon joined by Courtney Nevin and Alex Chidiac.
However, it would be Mexico who finished with a flurry, with a shot from distance forcing Mackenzie Arnold into an excellent save, pushing the ball past the left post.
In injury-time, Mexico would snatch a winner through the strike of substitute Diana Ordóñez, who fired the ball past the stretched leg of Mackenzie Arnold.
Attention now turns to Tuesday night, where the two sides will face off again at Parramatta's CommBank Stadium.
CommBank Matildas: 0
Mexico: 1 (Ordonez 90+2')
CommBank Matildas: 1. Mackenzie Arnold (GK), 3. Winonah Heatley, 7. Steph Catley (24. Charlize Rule), 8. Kaitlyn Torpey (2. Courtney Nevin), 9. Caitlin Foord, 10. Emily van Egmond (13. Alex Chidiac), 11. Mary Fowler, 14. Alanna Kennedy, 17. Amy Sayer (16. Hayley Raso), 20. Sam Kerr, 21. Ellie Carpenter (C)
Unused substitutes: 5. Jamilla Rankin, 6. Clare Wheeler, 12. Chloe Lincoln (GK), 15. Alana Murphy, 18. Ilona Melegh (GK), 19. Leticia McKenna, 22. Isabel Gomez, 25. Holly McNamara, 26. Remy Siemsen
Mexico: 21. Esthefanny Torres (GK), 4. Rebeca Rodriguez (C), 6. Reyna Reyes, 7. Maria Morales (22. Diana Ordonez), 8. Alexia Alvarado, 10. Kiana Hernandez (16. Karla Castillo), 14. Greta Casas, 18. Nancy Lopez (11. Alice Gallegos), 19. Angelique Pavon (9. Veronica Ang), 20. Nicolette Sippel (24. Ivonne Cortes), 23. Kimberly Cubero
Unused substitutes: 1. Itzel Loza (GK), 2. Vaitiare Salas, 5. Nina Nicosia, 12. Bianca Castro (GK), 13. Karol Castaneda, 15. Jasmine Casarez, 17. Fatima Sanchez